Added Frontend-30, a site with 30 web challenges to solve with projects

[SofiaBargues]

Added https://frontend-30.vercel.app/ site

Description

30 progressive frontend challenges to solve with projects

Motivation and Context

How Has This Been Tested?

Previewed

Types of changes

• [ ] Content Update (change which fixes an issue or updates an already existing submission)
• [x] New Article (change which adds functionality)
• [ ] Documentation change

Checklist:

• [x] My code follows the code style of this project.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have made checks to ensure URLs and other resources are valid